We extracted the schemas and vocabularies used in the RDF graphs exposed through \(\approx 20\)  SPARQL endpoints by different consortia. The entire list of the different linked data projects and details about sample RDF Graphs extracted are shown in Table  REF. These RDF graphs include popular biomedical data sources such as DrugBank [1]}, Kyoto Encyclopedia of Genes and Genomes (KEGG) [2]}, PharmGKB [3]}, Comparative Toxicogenomics Database (CTD) [4]}, exposed by the Bio2RDF consortium [5]}, UniProt [6]}, ChEMBL [7]}, and Reactome [8]}, exposed by the EBI-RDF consortium [9]}, and other sources such as The Cancer Genome Atlas (TCGA) [10]}, PubChem [11]}, and WikiPathways [12]}. It should be noted that some of these projects (e.g., Bio2RDF [5]}) have reprocessed publicly available data and knowledge published by other groups (e.g., DrugBank [1]}), whereas in some cases data publishers themselves use Semantic Web technologies to provide access to their proprietary data as linked data (e.g., the European Bioinformatics Institute (EBI) RDF Platform [9]}).
